Railway track switch control apparatus

Abstract

A railway track switch, also known as a switch machine, is controlled by a microprocessor switch lock connected to the electric switch lock of the switch machine and permits the switch machine to be unlocked so that the track switch points may be thrown, as by a hand-throw mechanism, to permit movement of a train between main and secondary tracks. The switch lock is connected to a cut section repeater of the track circuit adjacent to the track switch. An overlay track circuit connected to the main tracks indicates occupancy in the vicinity of the track switch. The microprocessor receives signals from the repeater, the overlay circuit and the electric switch lock of the switch machine indicating track occupancy and requests to unlock the track switch so that the switch points may be moved. Signals are also received from a timer as to specific, selected delay times set by the user before unlocking the switch. An interface also controls the microprocessor to decode occupancy and other track codes, transmitted by the track circuits and received by the repeater, as are selected by the user to enable the apparatus to be used with any track circuit communication code protocol. The microprocessor cooperates with a hardwired counter and is programmed to provide continuous checks for vital operation.

I claim: 
     
       1. Apparatus for unlocking a track switch, said track switch providing an unlocking request output when an unlocked condition is requested, said track switch being disposed adjacent a section of main tracks having successive sections separated by insulated joints to enable a train to move between said main tracks and secondary tracks, a repeater connected to said main tracks on opposite sides of the one of said joints for said section which has said track switch adjacent thereto for receiving and transmitting track codes representing the presence and lack of train occupancy in said section for controlling wayside signals, said apparatus comprising switch lock means including microprocessor means, said switch lock means being connected in controlling relationship with said track switch and said repeater, said microprocessor means having means for vitally checking its operation for enabling said microprocessor means to provide outputs for enabling the unlocking of said track switch and said repeater for the transmission of signals operative to clear said wayside signals only in the absence of a failure of said microprocessor means, said microprocessor means also having means responsive to said unlocking request output for inhibiting said repeater from the transmission of the track codes operative to clear said wayside signals, said microprocessor means further having means responsive to said track occupancy signals from said repeater indicative of the lack of occupancy and to said unlocking request output for generating the unlocking enabling output, said switch lock means having vital driver means for generating signals for enabling said repeater and unlocking said track switch, and means interfacing said vital driver means and said microprocessor means for providing said unlocking enabling and transmission enabling outputs to said vital driver means and for controlling said microprocessor means. 
     
     
       2. The invention according to claim 1 including in said switch lock means, overlay circuit means providing inputs to said microprocessor means indicative of trains on said sections of said main track adjacent to said track switch, said microprocessor means including means responsive to the output of said overlay circuit means for providing said unlocking enabling output when the presence of a train is detected by said overlay circuit means and said repeater receives track codes representing train occupancy in said sections. 
     
     
       3. The invention according to claim 2 wherein said switch lock means further comprises timer means for providing outputs representing a selected time delay, and said microprocessor means including means for providing said unlocking enabling output after said predetermined time delay when said overlay circuit means output represent the lack of occupancy of a train and said repeater track codes represent occupancy in said sections. 
     
     
       4. The invention according to claim 1 wherein said microprocessor means has means for decoding said track codes, and said interfacing means includes means for selectively enabling said microprocessor means to decode selected track codes used in the railroad territory having said track switch. 
     
     
       5. The invention according to claim 4 wherein said interfacing means has a plug board for receiving jumpers to provide outputs representing said selected track codes. 
     
     
       6. The invention according to claim 1 wherein said switch lock means further comprises counter means for repetitively counting instructions and timing signals produced in said microprocessor means and producing outputs corresponding to counts accumulated in said counter means, and said checking means including means for verifying the operation of said microprocessor means in response to the outputs from said counter means. 
     
     
       7. The invention according to claim 1 wherein said vital driver means is connected to said repeater and said track switch for applying said enabling signals thereto when operated by repetitive signals having a certain frequency, and said microprocessor means including means for generating said enabling outputs as repetitive signals having said certain frequency and applying said last-named signals to said vital driver means. 
     
     
       8. The invention according to claim 1 wherein said track switch has means for providing an output representing a request to unlock said switch, and said microprocessor means has means responsive to said unlock request output for providing said unlock enabling output only when said unlock request output is present. 
     
     
       9. The invention according to claim 8 wherein a plurality of said track switches are provided for switching trains between said section of said maintracks and different ones of a plurality of secondary tracks, and means for providing the unlock request when either of said switch means provides an output representing a request to unlock. 
     
     
       10. The invention according to claim 1 wherein said switch lock means further comprises watchdog timer means for resetting said microprocessor means unless reset within a given interval of time, and wherein said microprocessor means has means for resetting said watchdog timer means within said given period of time only so long as a microprocessor means is operative. 
     
     
       11. The invention according to claim 1 wherein said switch lock means has timer means operative to enable said unlocking output to be provided for a predetermined period of time.